Copper cleaning composition



3, 2% Patented Oct. 14, 1947 UNITED STATES PATENT OFFICE COPPER CLEANING COMPOSITION Esther M. Terry, Drexel Hill, and Morris Kaplan, Philadelphia, Pa.

No Drawing. Application September 7, 1945, Serial No. 615,067

- 1 Claim.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) This invention relates in general to the cleaning of copper and copper containing materials, and in particular to a composition of matter for use therein.

It is another object to provide a new copper cleaning composition.

Further objects and advantages of this invention as well as its use and operation will be apparent from the following description and claim.

According to this invention copper or a copper containing article is cleaned by treating it under conditions hereinafter to be described with a substantially homogeneous cleaning agent comprising an acid, an oxidizing agent and a brightening agent, with or without the addition of a diluent.

A wide variety of acids may be used in the cleaning agent, including for example, acids as widely difierent in characteristics as w}, phosphorimacid, formic acid and the like. There may be used both organic and inorganic acids either alone or in combinations; likewise there may be used oxidizing and non-oxidizing acids.

The purpose of the acid in the cleaning agent is to dissolve the readily acid-soluble constituents of the corrosion from the surface of the copper containing article. Asan additional advantage, the acid serves to stabilize the cleaning agent, in which capacity it is effective when the cleaning agent contains an oxidizing agent which is unstable under neutral or alkaline conditions.

It will be understood that there is wide freedom of'choice in the selection of a suitable acid, and that there is no limitation to specific acids set forth in the specification.

For the oxidizing agent there is used a moderately strong oxidizing agent, either organic or inorganic. The purpose of the oxidizing agent is twofold: first, it oxidizes the relatively insoluble cuprous compounds to the relatively more soluble and more readily attacked cupric compounds; and second, it very slowly oxidizes copper itself from the surface of the copper containing article, thus encouraging a flaking oii action. The flaking oif action removes from the surface of the article various insoluble and inert foreign matter which frequently is entrapped by the naturally forming tarnish or corrosion, and presents a new, and accordingly a bright, clean surface. An oxidizing agent which has been found admirably suited to these purposes is hydrogen peroxide, and in the presently preferfid embodiment of the invention hydrogen peroxide is now being used; however, it will be understood that the selection of the oxidizing agent is not limited thereto.

The third operative constituent of the cleaning agent is a brightening agent comprising substances such as, for example acetic acid, cream Of tartar (potassium acid tartrate) citric acid,

ycpllic acid and the like. In general it may be said that the brightening agent is a weakly acidic compound such as an organic acid or an organic acid salt; however, it is obvious that other nonorganic or non-acidic substances may be used for this purpose and that their selection is within the skill of one trained in the art.

It will be seen from an examination of the constituents described herein that numerous of the brightening agents may also be used as the acidifying agent, and accordingly it is within the scope of this invention that there may be provided a cleaning composition comprising an oxidizing agent and an acidifying-brightening agent; however it is usually the case that more advantages may be obtained when two different compounds are used for these two difierent purposes and the combined efiects of the two compounds are realized.

When the cleaning composition is dissolved in water or an aqueous solution to provide a cleaning solution in which the article may be cleaned by simple immersion there may optionally be added a detergent or wetting agent to increase the efiectiveness oi the cleaning agent in removing tarnish or corrosion from cracks and crevices. Alternatively, the cleaning composition may be carried in a. conventional paste or cream emulsion, and in this for'niis 'particliilarly adapted for local application where the article contains elements which might be harmed by immersion in a low viscosity solution. Various other vehicles and diluents will be obvious and will have obvious advantages for particular desired results.

The following specific example is given to illustrate the invention as adapted to provide a cleaning solution for the removing of tarnish and corrosion by immersion. It will be understood, however, that this example is given solely for the purposes of illustration, and that the scope of the invention is not to be limited to or by the scope of this example.

A liquid cleaning solution is prepared by dissolving 5 parts by weight of sulfuric acid 4 /2 parts of hydrogen peroxide (BWnd 3 parts acetic acid (glacial) in 87% parts of water. The rtWlatively stable, to the extent that even upon being maintained at about 35 to 40 C. for sixteen 8-hour periods on successive 'days this solution will lose only about 3.3% of its original strength as determined by available hydrogen peroxide. After intermittent use for several months during which time the solution may accumulate various types of impurities including corrosion products of copper and its alloys, paint, oil, grease, dirt, and the like, there will be no noticeable decrease in efiiciency.

grams of this cleaning solution is sufficient to clean successively a number of copper surfaces Winni g approximately 200 square inches in 2,42aeo4 sion in the cleaning solution. Le;a d, alymimrm,

The solution has only slight efiect on the surface of the copper containing article, and immersion of copper in the solution for minutes at C. causes a loss of about 9 mg. of copper per square inch.

The method of using this cleaning solution will vary, depending on the nature of the article to be cleaned, the type of soil or corrosion products, and'the degree and character of cleaning desired. Where the cleaning solution is used on extremely diificult cases of corrosion or the like, or where a more rapid cleaning is desired, the cleaning bath may advantageously be heated. By protracting the immersion time, if desired, a variety of surface finishes may be obtained. For average conditions the following procedure will work satisfactorily.

An article to be cleaned is completely immersed in a bath of the cleaning solution for about 10 minutes at about C. When the tarnish is substantially dissolved or loosened, the article is removed from the bath and rinsed in a suitable manner either in 'a water bath or in running water. If a crust remains on portions of the surface it may usually be removed by brushing dflring the rinsing period. If necessary, a second immersion in the cleaning bath will remove final traces of tarnish, corrosion or other dirt.

By the use of this invention it is now possible to remove tarnish and the products of atmospheric corrosion as well as dirt and impurities of widely varying nature from articles and parts composed of copper and copper allo s. The in- 1mm without their disassembly when the copper is used in conjunction with wood, porcelain and other nonmetallic materials, and as well with numerous corrosion resisting metals. The articles may be cleaned rapidly, efiectively and safely with a minimum of effort and disturbance and a maximum thoroughness.

It is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope thereof as set forth in the appended claim.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

A copper cleaning composition comprising approximatel 5 parts by weight of sulphuric acid, 4 /2 parts; 30'% hyclrogen peroxide, 3 parts of acetic acidand 87 /2 parts of water.

ESTHER M. TERRY. I MORRIS KAPLAN.

\REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,154,468 Oplinger Apr. 18, 1939 2,172,171 Meyer et al Sept. 5, 1939 2,211,400 Wood Apr. 13, 1940 2,154,451 Hull Apr. 18, 1939 

